The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Luisa F. Cabeza - One of the best experts on this subject based on the ideXlab platform.
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Adaptation of Rammed Earth to modern construction systems: Comparative study of thermal behavior under summer conditions
Applied Energy, 2016Co-Authors: Susana Serrano, Alvaro De Gracia, Luisa F. CabezaAbstract:Abstract Buildings should be understood as a process that consumes energy in all their phases (design, construction, use and end-of-life) and, more specifically, the building envelope is clearly involved in all of them. For this reason, the International Energy Agency defines in its latest publication the improvement of building envelopes as one of the key points to reduce the energy consumption in buildings. In the present study, two sustainable construction systems based on Rammed Earth Walls are adapted to modern requirements to be thermally tested and compared against three Mediterranean conventional systems under summer conditions. The experimentation was done by performing several experiments in free floating and controlled temperature conditions at real scale in five cubicle-shape buildings with inner dimensions 2.4 × 2.4 × 2.4 m. The purpose of this study is to demonstrate that more sustainable construction systems can be used instead of conventional ones, with higher embodied energy, and achieve similar thermal response. Results show that the reduction of Rammed Earth Wall thickness strongly penalizes its thermal behavior. However, similar thermal response than conventional systems is reached when 6 cm of wooden insulation panels are added in the outer face of the cubicle-shape building.
Q. B. Bui - One of the best experts on this subject based on the ideXlab platform.
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Steel nail embedded in Rammed Earth Wall to support vertical loads: An investigation
Construction and Building Materials, 2020Co-Authors: Q. B. Bui, T. T. Bui, Malwen Jaffré, Loïc TeytuAbstract:Abstract Rammed Earth (RE) is a construction material manufactured by compacting the soil by layers in a formwork. This material has been the focus of numerous scientific researches in the last decades because of its sustainable properties and the heritage of RE buildings throughout the world. Several studies were performed to investigate different aspects of this material, however, there were few studies investigating on the capacity of nails on RE Walls. Indeed, this resistance is important when occupants want to hang furniture (photo frames, kitchen cabinets…). This paper presents firstly an experimental study on the capacity of smooth steel nails (without dowel) horizontally fixed on RE specimens to carry vertical loads. Different types of nails with different diameters (from 3.1 to 5 mm) were tested, at different anchorage lengths into the RE specimens (from 65 to 120 mm). The results showed that one nail could hang 200–1000 N of vertical load, depending on the type of nail, the anchored length and the loading rate. It was worth noting that the steel nails were excessively deformed after the test. A numerical model was developed to analyze the results. The numerical results showed that RE was first plasticized in certain zones and then the steel nails were also plasticized. Influences of the creep phenomenon was also observed and analyzed.
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characterizing the shear parameters of Rammed Earth material by using a full scale direct shear box
Construction and Building Materials, 2018Co-Authors: R Elnabouch, Q. B. Bui, Olivier Ple, Pascal PerrotinAbstract:Abstract Rammed Earth (RE) is one of the different techniques of Earth constructions. The RE Wall is built by compacting the soil in a formwork, layer after layer (about 10–15 cm thick for each layer). RE buildings are recognized for their very low embodied energy and their positive hygrothermal behaviour. Several recent studies have investigated RE material and among different aspects, the seismic performance remains an interesting topic that needs to be explored. In order to propose a robust model for seismic investigation, the shear characteristics of RE material should be appropriately determined. These shear characteristics include the cohesion, the friction angle of the intralayers and also the cohesion, the friction angle of the interlayers (between the layers) as a RE Wall contains multilayers. However, few studies have directly identified these parameters by experiments. This is the first time, to our knowledge, that a full-scale shear box (0.5 m width × 0.5 m length × 0.45 m height) was specifically developed to study the shear parameters of the Rammed Earth. This full-scale shear box was designed to reproduce the manufacturing conditions of a current Rammed Earth Wall in Europe (50-cm-thickness). Direct shear tests were performed both for intralayers and interlayers. The results showed that the shear strength obtained at the interlayers were about 80–90% of the corresponding values obtained at the intralayers. Finally, the influences of the moisture content and the size effect on the obtained results were also discussed.
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Modeling Rammed Earth Wall using discrete element method
Continuum Mechanics and Thermodynamics, 2016Co-Authors: T. T. Bui, Q. B. Bui, Ali Limam, J. C. MorelAbstract:Rammed Earth is attracting renewed interest throughout the world thanks to its "green" characteristics in the context of sustainable development. Several research studies have thus recently been carried out to investigate this material. Some of them attempted to simulate the Rammed Earth's mechanical behavior by using analytical or numerical models. Most of these studies assumed that there was a perfect cohesion at the interface between Earthen layers. This hypothesis proved to be acceptable for the case of vertical loading, but it could be questionable for horizontal loading. To address this problem, discrete element modeling seems to be relevant to simulate a Rammed Earth Wall. To our knowledge, no research has been conducted thus far using discrete element modeling to study a Rammed Earth Wall. This paper presents an assessment of the discrete element modeling's robustness for Rammed Earth Walls. Firstly, a brief description of the discrete element modeling is presented. Then the parameters necessary for discrete element modeling of the material law of the Earthen layers and their interfaces law following the Mohr-Coulomb model with a tension cut-off and post-peak softening were given. The relevance of the model and the material parameters were assessed by comparing them with experimental results from the literature. The results showed that, in the case of vertical loading, interfaces did not have an important effect. In the case of diagonal loading, model with interfaces produced better results. Interface characteristics can vary from 85 to 100% of the corresponding Earthen layer's characteristics.
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durability of Rammed Earth Walls exposed for 20 years to natural weathering
Building and Environment, 2009Co-Authors: Q. B. Bui, Jean Claude Morel, B Venkatarama V Reddy, W GhayadAbstract:This paper presents a study on the durability of different types of stabilised and unstabilised Rammed Earth Walls. These Rammed Earth Walls were constructed and exposed for 20 years to natural weathering, in a wet continental climate. None of these Walls have shown complete collapse to date. A method to measure the Rammed Earth Walls erosion by stereo-photogrammetry has been developed. The result shows that the mean erosion depth of the studied Walls is about 2 mm (0.5% Wall thickness) in the case of Rammed Earth Wall stabilised with 5% by dry weight of hydraulic lime and about 6.4 mm (1.6% Wall thickness) in the case of unstabilised Rammed Earth Walls. The stabilisation enables to not use any plaster to protect the Walls. In the case of the unstabilised Rammed Earth Walls, an extrapolated lifetime longer than 60 years can be assessed. This shows a potential for the use of unstabilised Rammed Earth in the similar climatic conditions with this study. The method of stereo-photogrammetry used to measure the erosion of Rammed Earth Walls on site may also help to calibrate and develop more pertinent laboratory test to assess the durability of Rammed Earth Wall.
Jacinto Canivell - One of the best experts on this subject based on the ideXlab platform.
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the use of non destructive testing to evaluate the compressive strength of a lime stabilised Rammed Earth Wall rebound index and ultrasonic pulse velocity
Construction and Building Materials, 2020Co-Authors: J J Martindelrio, Jacinto Canivell, Raul M FalconAbstract:Abstract The non-standardization of Rammed Earth construction involves the quality control of such a technique to be so troublesome that it is generally avoided. As a possible approach to improve the mentioned quality control, this paper deals with a series of univariate and multivariate statistical analyses concerning the correlation between a pair of non-destructive testings (rebound index and ultrasonic pulse velocity) and the compressive strength of a specific composition of Rammed Earth. Both non-linear (univariate) and linear (multivariate) regression models are established so that the variability of the compressive strength is accurately explained by means of both kind of non-destructive testings.
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Considerations on the physical and mechanical properties of lime-stabilized Rammed Earth Walls and their evaluation by ultrasonic pulse velocity testing
Construction and Building Materials, 2018Co-Authors: Jacinto Canivell, J. J. Martín-del-río, F. J. Alejandre, J. García-heras, Alberto Jimenez-aguilarAbstract:Abstract This study examines the influence of moulding moisture content on the compressive strength, dry density and porosity of a Rammed Earth Wall, using ultrasound as a complementary technique. Non-parametric and multivariate statistical techniques were applied to analyse the behaviour of variables with a sufficiently large population. The statistical analysis demonstrated that excessive or insufficient moulding moisture content directly determines the physical-mechanical properties of such Walls. Ultrasound was confirmed as a valid technique for assessing the quality of a Wall, since its response, albeit with certain limitations, was consistent with physical-mechanical properties.
Raul M Falcon - One of the best experts on this subject based on the ideXlab platform.
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the use of non destructive testing to evaluate the compressive strength of a lime stabilised Rammed Earth Wall rebound index and ultrasonic pulse velocity
Construction and Building Materials, 2020Co-Authors: J J Martindelrio, Jacinto Canivell, Raul M FalconAbstract:Abstract The non-standardization of Rammed Earth construction involves the quality control of such a technique to be so troublesome that it is generally avoided. As a possible approach to improve the mentioned quality control, this paper deals with a series of univariate and multivariate statistical analyses concerning the correlation between a pair of non-destructive testings (rebound index and ultrasonic pulse velocity) and the compressive strength of a specific composition of Rammed Earth. Both non-linear (univariate) and linear (multivariate) regression models are established so that the variability of the compressive strength is accurately explained by means of both kind of non-destructive testings.
Mark Luther - One of the best experts on this subject based on the ideXlab platform.
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Validated model and study of a Rammed Earth Wall building
2004Co-Authors: P. Taylor, Robert Fuller, Mark LutherAbstract:A 2100 m2 (GFA) two-storey Rammed Earth building was built on the Thurgoona campus of Charles Sturt University in 1999. The building is novel both in the use of materials and equipment for heating and cooling. The climate at Wodonga can be characterised as hot and dry, so the challenge of providing comfortable working conditions with minimal energy consumption is considerable. This paper describes a thermal model of one of the second-storey offices on the west-end of the building. The simulation software, TRNSYS, has been used to predict office temperatures and comparisons are made between these and measurements made over a typical week in summer. Reasonable agreement has been achieved under most conditions. The model has been used to investigate key building parameters and strategies, including night flushing, to improve the thermal comfort in the office.
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Evaluating Rammed Earth Walls: a case study
Solar Energy, 2003Co-Authors: P. Taylor, Mark LutherAbstract:The following research has been undertaken as a response to the recent controversy regarding the suitability of Rammed Earth Wall construction as an effective building envelope in regard to its thermal performance. The R-value for Rammed Earth Walls is low hence they might be expected to conduct heat into a building during summer. However the large mass of these Walls and the associated thermal lag in heat transfer from outside to inside may result in the Walls performing satisfactorily in a building which is only occupied during working hours. Internal Rammed Earth Walls may act as moderators of large diurnal temperature swings helping to produce an even comfortable temperature within a building. Empirical (in situ) measurements of temperature and heat flux were taken on the Walls of an existing Rammed Earth office building in New South Wales, Australia during the summer. An analysis was performed which established a methodology to measure the heat flow associated with the Walls, floor, ceiling, windows and infiltration for one office during occupied hours and the net energy transferred between the office and these elements was established. During this time the Earth Walls performed well. External Walls were found to transmit comparatively little heat to the office and the internal Walls absorbed heat during this time. Diffuse sky radiation transmitted by the window and infiltration are both likely to be important factors in the summer heat load.
